Cytochrome c plays an essential role in the energy-yielding electron transfer reactions of mitochondria. Glyceraldehyde 3-P dehydrogenase (GAPDH) is a key glycolytic enzyme important in carbohydrate metabolism and in energy production. This enzyme is especially active in muscle and may be differentially regulated. Our long-term goals are to clone and to determine the DNA sequence of a number of cytochrome c genes and GAPDH genes, as well as their pseudogenes, and to obtain fundamental information on the evolution of genes and pseudogenes. The following organisms, which are representatives of evolutionary periods between major divergence events, will be covered by this and earlier studies: human, monkey, rat, chicken, frog, tuna fish, fruit fly, snail, rice, Arabidopsis, ginkgo and yeast. Two additional goals of this proposal are (a) to study the muscle specific regulation of the GAPDH gene in the fruit fly; and (b) to study the regulation of expressed rat GAPDH pseudogenes that we have discovered. The reasons why we have chosen cytochrome c genes and GAPDH genes for the initial studies are: (a) Over 90 cytochrome c protein sequences and about 10 GAPDH protein sequences are known. (b) Both proteins are relatively highly conserved in both the primary and tertiary structures. (c) Cytochrome c and GAPDH are present in all eucaryotes. For the preceding three reasons, cytochrome c has already served as a useful model for molecular evolutionary analysis. (d) Also, a large number of clones carrying cytochrome c-like or GAPDH-like pseudogene sequences have been isolated in our laboratory. We plan to study more genes and pseudogenes by using a new approach for the identification of a functional gene from among many pseudogenes.